A melt approach to the synthesis of catena-phosphorus dications to access derivatives of [P6Ph4R4]2+.
Explore the source record for details and available documents.
Journal Article↗
Biomedical subjects
Jan J Weigand
Publications and source records attributed to Jan J Weigand.
N-nitroso- and N-nitraminotetrazoles.
N-Nitroso- (5a,c) and N-nitraminotetrazoles (6a-c) were synthesized from the corresponding aminotetrazoles (3a-c) either by the direct nitration with acetic anhydride/HNO3 or by dehydration of the corresponding nitrates (4a-c) with concentrated sulfuric acid. The conversion of the N-nitrosoaminotetrazoles (5a,c) with peroxytrifluoroacetic acid (CF3CO3H) yielded the corresponding nitramines in high yield (6a (82%), 6c (80%)). The N-nitroso- (5a,c) and N-nitraminotetrazoles (6a-c) have been fully characterized by vibrational (IR, Raman) and multinuclear NMR spectroscopy (14N/15N, 1H, 13C), mass spectrometry, and elemental analysis. A detailed discussion of the 15N chemical shifts and 1H-15N coupling constants is given. The molecular structures in the solid state were determined by single-crystal X-ray diffraction (3a,c; 5a,c; 6a-c) and a detailed discussion of the molecular structures will be presented. Furthermore, the structure and bonding as well as N,N rotational barriers are discussed on the basis of theoretically obtained data (B3LYP/6-31G(d,p), NBO analysis). In the case of two N-nitraminotetrazoles (6a,c) the physicochemical properties (e.g., D, P, delta(f)H degrees) were evaluated. The heat of formation was calculated to be positive for 6a and 6c (+2.8 and +85.2 kcal mol(-1), respectively) and the calculated detonation velocity with 5988 (6a) and 7181 (6c) m s(-1) reaches values of TNT and nitroglycerin.
Journal Article↗
BTA copper complexes.
Cupric oxide is one of the most important additives used (a) to catalyze decomposition reactions in gas generators to obtain cooler reaction gases, (b) as burning enhancer for ammonium perchlorate-based composite propellants, and (c) as coloring agent in pyrotechnics. In this context, the reaction of Cu(2+) ions in aqueous ammonia solution with bis(tetrazolyl)amine (H(2)bta) was investigated. Depending on the reaction conditions three complexes were obtained: Cu(bta)(NH(3))(2) (1), Cu(bta)(NH(3))(2).H(2)O (2), and (NH(4))(2)Cu(bta)(2).2.5H(2)O (3). The crystal structures of 1 and 2 are discussed with respect to the coordination mode of the dianion of N,N-bis(1(2)H-tetrazol-5-yl)-amine (bta), which mediates in the case of 1 and 2 weak superexchange interactions between the adjacent magnetic transition-metal Cu(II) cations. These antiferromagnetic interactions result from 1D copper chains over an hidden azide end-to-end bridge. Interestingly, the structural arrangement of 1 completely changes in the presence of crystal-bound water. Moreover, some physicochemical properties (e.g., heat of formation, friction, and impact sensitivity, DSC) of these complexes with respect to high-energetic materials are discussed.
Journal Article↗
3,5-Dimethyl-1,3,5-oxadiazane-2,4,6-trione: short intermolecular contacts determining the crystal packing.
In the title compound, C5H6N2O4, the molecules lie across a crystallographic mirror plane. The compound lacks traditional hydrogen-bond donors, and hence crystals are held together by unusual C=O...O, O...C and weak C-H...O interactions, forming layers. Adjacent layers are arranged in an antiparallel manner, yielding an ABA layer sequence. The intermolecular contacts are quite short; a topological analysis of charge density based on density-functional-theory calculations was used for consideration of these short contacts and indicated a strong attractive bonding closed-shell interaction between these atoms in the crystal structure.
Journal Article↗
The dianion of 5-cyanoiminotetrazoline: C2N62-.
Several salts (alkali, Pd(NH(3))(3), and (i)PrNH(2)) of 5-cyanoiminotetrazoline (C(2)N(6)(2-), 5-cyanoiminotetrazolinediide, CIT) were investigated. A full characterization by means of X-ray, Raman, NMR techniques, mass spectrometry, and elemental analysis is presented for the (i)()PrNH(2) (4), Cs (5), and Pd(NH(3))(3) (6) salts. The CIT dianion represents a nitrogen-rich binary CN dianion, and 5 forms monoclinic crystals (a = 7.345(2) Angstroms, b = 9.505(2) Angstroms, c = 10.198(2) Angstroms, beta = 92.12(3) degrees, space group P2(1)/n, Z = 4). DSC and in situ temperature-dependent X-ray diffraction measurements of the cesium salt 5 revealed an astonishing thermal stability accompanied by a reversible phase transition from the low-temperature alpha modification to the metastable beta modification at 253 degrees C. Above the melting point (334 degrees C), the cesium salt decomposes yielding cesium azide and cesium dicyanamide, which decomposes under further heating under release of nitrogen. The reaction of Cs(2)CIT with SO(2) resulted in the surprising formation of a new cesium salt with the 5-cyaniminotetrazoline-1-sulfonate dianion (Cs(2)CITSO(3).SO(2) (7)). 7 crystallizes in the monoclinic space group P2(1) with one SO(2) solvent molecule (a = 8.0080(2) Angstroms, b = 8.0183(2) Angstroms, c = 9.8986(3) Angstroms, beta = 108.619(1) degrees, Z = 2). The structure and bonding of the 10pi dianion are discussed on the basis B3LYP/aug-cc-pvTZ computations (MO, NBO), and the three-dimensional array of the cesium salts with respect to the Cs(delta) (+)-N(delta)(-) in 5 compared to the Cs(delta)(+)-N(delta)(-) and Cs(delta)(+)-O(delta)(-) in 7 is discussed. Due to the expected rich bonding modes of the CIT anions, the coordination chemistry with palladium was also studied, yielding monoclinic crystals of [Pd(CIT)(NH(3))(3)].H(2)O (6, a = 7.988(2) Angstroms, b = 8.375(2) Angstroms, c = 13.541(3) Angstroms, beta = 104.56 degrees, space group P2(1)/n, Z = 4). In the solid state, the complex is composed of dimers, showing two agostic interactions and an unusual close interplanar pi-pi stacking of the tetrazole moiety of the CIT ligand.
Journal Article↗
Nitro(nitroso)cyanomethanides.
Explore the source record for details and available documents.
Journal Article↗
Derivatives of 1,5-diamino-1H-tetrazole: a new family of energetic heterocyclic-based salts.
1,5-Diamino-1H-tetrazole (2, DAT) can easily be protonated by reaction with strong mineral acids, yielding the poorly investigated 1,5-diaminotetrazolium nitrate (2a) and perchlorate (2b). A new synthesis for 2 is introduced that avoids lead azide as a hazardous byproduct. The reaction of 1,5-diamino-1H-tetrazole with iodomethane (7a) followed by the metathesis of the iodide (7a) with silver nitrate (7b), silver dinitramide (7c), or silver azide (7d) leads to a new family of heterocyclic-based salts. In all cases, stable salts were obtained and fully characterized by vibrational (IR, Raman) spectroscopy, multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, X-ray structure determination, and initial safety testing (impact and friction sensitivity). Most of the salts exhibit good thermal stabilities, and both the perchlorate (2b) and the dinitramide (7c) have melting points well below 100 degrees C, yet high decomposition onsets, defining them as new (7c), highly energetic ionic liquids. Preliminary sensitivity testing of the crystalline compounds indicates rather low impact sensitivities for all compounds, the highest being that of the perchlorate (2b) and the dinitramide (7c) with a value of 7 J. In contrast, the friction sensitivities of the perchlorate (2b, 60 N) and the dinitramide (7c, 24 N) are relatively high. The enthalpies of combustion (Delta(c)H degrees ) of 7b-d were determined experimentally using oxygen bomb calorimetry: Delta(c)H degrees (7b) = -2456 cal g(-)(1), Delta(c)H degrees (7c) = -2135 cal g(-)(1), and Delta(c)H degrees (7d) = -3594 cal g(-)(1). The standard enthalpies of formation (Delta(f)H degrees ) of 7b-d were obtained on the basis of quantum chemical computations using the G2 (G3) method: Delta(f)H degrees (7b) = 41.7 (41.2) kcal mol(-)(1), Delta(f)H degrees (7c) = 92.1 (91.1) kcal mol(-)(1), and Delta(f)H degrees (7d) = 161.6 (161.5) kcal mol(-)(1). The detonation velocities (D) and detonation pressures (P) of 2b and 7b-d were calculated using the empirical equations of Kamlet and Jacobs: D(2b) = 8383 m s(-)(1), P(2b) = 32.2 GPa; D(7b) = 7682 m s(-)(1), P(7b) = 23.4 GPa; D(7c) = 8827 m s(-)(1), P(7c) = 33.6 GPa; and D(7d) = 7405 m s(-)(1), P(7d) = 20.8 GPa. For all compounds, a structure determination by single-crystal X-ray diffraction was performed. 2a and 2b crystallize in the monoclinic space groups C2/c and P2(1)/n, respectively. The salts of 7 crystallize in the orthorhombic space groups Pna2(1) (7a, 7d) and Fdd2 (7b). The hydrogen-bonded ring motifs are discussed in the formalism of graph-set analysis of hydrogen-bond patterns and compared in the case of 2a, 2b, and 7b.
Journal Article↗
Mono-, di-, and tricoordinated phosphorus attached to a N-N unit: an experimental and theoretical study.
N,N',N'-[Tris(trimethylsilyl)]hydrazino-diphenylphosphane, (TMS)2 N-(TMS)N-PPh2 (1), and N,N',N'-[tris(trimethylsilyl)]hydrazino-phenyl(chloro)phosphane, (TMS)2 N-(TMS)N-P(Cl)Ph2 (2), were obtained in the reaction of bis-[lithium-tris(trimethylsilyl)hydrazide] with Ph(n)PCl(3 - n) (n = 1, 2). The structure and bonding of both species are discussed on the basis of experimentally observed (X-ray, Raman, NMR, and MS) and theoretically obtained data (B3LYP/6-31G(d,p), NBO analysis). Oxidation with sulfur and selenium results in the formation of (TMS)2 N-(TMS)N-P(S)Ph2 (4), (TMS)2 N-(TMS)N-P(Se)Ph2 (5), (TMS)2 N-(TMS)N-P(S)Ph(Cl) (6), and (TMS)2 N-(TMS)N-P(Se)Ph(Cl) (7). Moreover, the thermal decomposition of N,N',N'-[tris(trimethylsilyl)]hydrazine-dichlorophosphane, (TMS)2 N-(TMS)N-PCl2 (3) and the reaction with magnesium have been investigated. The formation and molecular structure of the novel MgCl2(THF)2 x 2Mg[(TMS)NP(O)2 N(TMS)2](THF) (8) salt containing the hitherto unknown (TMS)NP(O)2 N(TMS)2(2-) anion are discussed. DFT calculations (B3LYP/6-311+G(3df,2p)//B3LYP/6-31G(d,p)) are used to evaluate the bonding, ground-state structures, and energy landscape for the different isomers of 3: the thermodynamics and kinetics of the successive elimination of chlorotrimethylsilane (TMS-Cl) resulting in the formation of covalent azide analogues such as TMS-PNN or TMS-NNP.
Journal Article↗
1,5-diamino-4-methyltetrazolium dinitramide.
The highly friction-sensitive 1,5-diamino-4-methyltetrazolium dinitramide was synthesized by a metathetical reaction of the corresponding iodide and silver dinitramide. An intriguing interaction of one nitro group with the tetrazolium cation was found as a crystal structure determining feature (X-ray determination), and the chemical bond is discussed on the basis of the theory of atoms in molecules (AIM).
Journal Article↗
Blue alkali dinitrosomethanides: synthesis, structure, and bonding.
Explosive alkali dinitrosomethanides (M[HC(NO)2]; M = Li, Na, K, Cs) were prepared in a new, simple, high-yielding synthetic procedure, fully characterized, and shown to be stable at ambient temperature. Alkali dinitrosomethanides are of widespread interest to pharmaceutical and materials scientists alike.
Journal Article↗